JPS63100999U - - Google Patents

Description

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention,
2A and 2B are graphs showing that the V/F pattern is switched by the switching operation of the rated voltage switch in the embodiment circuit shown in FIG. 1. 2: AC power supply, 3: Rectifier, 4: Smoothing capacitor, 5: VVVF inverter, 6: Induction motor,
10: Test voltage generation circuit, 11: Signal generator,
12: Signal switcher, 13: Frequency setter, 14
: V/F pattern generation circuit, 15: PWM control circuit, 16: Current transformer, 17: Impedance calculation circuit, 18: Motor capacity determination circuit, 21: Rated voltage switching device.

Claims (1)

[Scope of utility model registration request] Multiple sets of correlations between AC voltage and frequency output by an inverter that drives an AC motor at variable speed are determined, and a voltage/frequency pattern is generated that can output a desired one of the correlations using an external signal. means, a test voltage generating means for causing the voltage/frequency pattern generating means to output a test voltage low enough to prevent the AC motor from rotating prior to operation of the AC motor, and a test voltage generating means for outputting a test voltage to the AC motor in response to the test voltage. capacity determining means for determining the capacity of the AC motor from the flowing current; a circuit for inputting the output signal of the capacity determining means to the voltage/frequency pattern generating means; and a circuit for inputting the output signal of the capacity determining means to the voltage/frequency pattern generating means; 1. A control device for an inverter for driving a motor, comprising means for inputting data to a pattern generating means.